import math

point = map(float, raw_input().split())
x1 = point[0]
y1 = point[1]
x2 = point[2]
y2 = point[3]

distance = math.sqrt((x2 - x1) ** 2 + (y2 - y1) ** 2)
print distance import math math point = map(float, raw_input().split()) point map(float, raw_input().split()) map float raw_input().split() ().split () raw_input split x1 = point[0] x1 point[0] point 0 y1 = point[1] y1 point[1] point 1 x2 = point[2] x2 point[2] point 2 y2 = point[3] y2 point[3] point 3 distance = math.sqrt((x2 - x1) ** 2 + (y2 - y1) ** 2) distance math.sqrt((x2 - x1) ** 2 + (y2 - y1) ** 2) math.sqrt math sqrt (x2 - x1) ** 2 + (y2 - y1) ** 2 (x2 - x1) ** 2 x2 - x1 x2 x1 2 (y2 - y1) ** 2 y2 - y1 y2 y1 2 print x1 = point[0] point[0] x1 x2 = point[2] point[2] x2 y1 = point[1] point[1] y1 y2 = point[3] point[3] y2 point = map(float, raw_input().split()) map(float, raw_input().split()) point distance = math.sqrt((x2 - x1) ** 2 + (y2 - y1) ** 2) math.sqrt((x2 - x1) ** 2 + (y2 - y1) ** 2) distance
import math

point = map(float, raw_input().split())
x1 = point[0]
y1 = point[1]
x2 = point[2]
y2 = point[3]

distance = math.sqrt((x2 - x1) ** 2 + (y2 - y1) ** 2)
print distance